Performance of an inductive fault current limiter employing BSCCO superconducting cylinders

AC losses in high pressure synthesized MgB2bulk rings measured by a transformer method

“…The procedure for AC loss determination in samples with induced current relies on measuring, with the help of the Hall-probe technique (figure 1(a)), the magnetic flux density as a function of the instantaneous current in the primary coil. This method has been previously used by the authors of the present work to measure AC losses in BSCCO cylinders [14,15]. The main advantages of this method are that (i) high currents of up to several tens of thousands of amperes can be achieved in a superconductor using conventional laboratory equipment, (ii) no current terminals or measuring contacts to a superconductor are required and (iii) the measurement results are not influenced by heating due to losses in the contacts.…”

“…Measurements of AC losses in bulk superconducting samples with a transport current are usually based on the four-point method which requires a high current supply of up to tens or even hundreds of thousands of amperes and high quality contacts. One contactless method suitable for samples in the form of a closed loop (hollow cylinder, ring or short-circuited coil) is based on using the transformer configuration (figure 1(a)) [14,15]. A superconducting closed loop forms the secondary coil of a transformer in which the primary coil is connected with an AC source.…”

Superconducting FCL: Design and Application

“…1) increase of the homogeneity of a superconductor resulting in the increase of the formation time of the domain and in the decrease of its temperature [40]- [43]; 2) stabilization of a superconductor by normal conducting materials; note that this measure reduces the resistance of the switching element in the normal state and requires longer elements [3], [35]; 3) shunting entire device by an external resistor or an inductor [15], [17], [44], [45]; 4) introducing an additional coil closed by a resistive load [17], [45]; 5) employing superconducting elements with a smooth current-voltage characteristic [46].…”

Measurement of critical current in superconducting rings

“…Under these conditions, the flux is not cancelled in the core and the impedance limits the current flowing in the circuit. After the failure has been repaired, the current induced in the superconductor is again lower than the critical value, and the normal working conditions are recovered, with flux cancellation and zero impedance [1][2][3][4].…”